Do Americans prefer economic populism or cultural populism? Are voters more likely to blame billionaires for their problems — or to scapegoat immigrants?

If Democrats stay on their current trajectory and we end up with a November showdown between President Trump and Vermont Sen. Bernie Sanders, we’re about to find out.

If the 2016 election provided any lessons, it’s that nobody can really say for sure whether a candidate is “electable.” Grand pronouncements that Trump couldn’t win were wrong. Grand pronouncements that Sanders can’t win could be wrong. We simply don’t know.

What we do know, however, is that Democrats need to win over swing voters in the Midwest if the party is going to dethrone Trump. To understand how a Sanders candidacy might play out in those crucial areas, it’s worth zooming in on a microcosm of a divided Midwest: the 1st Congressional District in southern Minnesota.

It’s a 50/50 district. In the 2016 election, the Democrat won by about 2,500 votes. In the 2018 election, the Republican won by fewer than 1,500 votes, a margin of less than half a percentage point. But the 2018 election provided a crucial insight: Voters in Midwestern swing states can get more fired up by culture wars — of the kind instigated by Trump — than by the economic populism offered by Sanders.

Use the Post Opinions Simulator to pick a state and see what might happen in upcoming primaries and caucuses.

Anchored by the city of Rochester, Minnesota’s 1st District has two distinct blocs of voters. First, there are the tens of thousands of doctors, nurses and support staff who work in Rochester’s economic powerhouse: the world-leading Mayo Clinic health-care system. Second, there are farmers. The district is home to roughly 18,000 farms.

In the 2018 midterms, voters faced a choice between Jim Hagedorn, the son of a congressman who spent most of his career working political jobs in Washington, and Dan Feehan, a combat veteran-turned-math teacher who served two tours in Iraq. Feehan was awarded the Bronze Star, the Army Commendation Medal with Valor and the Ranger Tab for his service.

One of the big issues in the campaign was that Trump’s trade war has been devastating the region’s soybean farmers for the past several years. They relied on China as their primary export market. Farmers who had spent decades building trade relationships with Chinese buyers were seeing those importers start buying from Minnesota’s competitors in places such as Brazil. Many farmers have openly acknowledged that Trump’s trade war is badly hurting them, and they are only able to stay afloat due to an economic bailout.

Feehan’s campaign focused on kitchen-table economic issues: expanding health care and ending Trump’s trade war so that farmers could regain their past prosperity without government support.

In short, the Democratic candidate was a heavily decorated combat veteran who had fought terrorists in Iraq and was pushing for open markets so that farmers wouldn’t need to rely on government bailouts.

He lost because Republicans absurdly branded him an anti-American, Soros-funded socialist and criticized him for being an unpatriotic American who supported terrorists. In attack ads, Feehan was criticized for two tweets he posted in support of Colin Kaepernick. “Tell Dan Feehan,” one ad concludes, “real patriots stand together.” Apparently two tweets can cancel out two tours in Iraq when it comes to that warped version of patriotism.

“This is a choice between whether or not we support our country, defend everything we believe in, or we turn it over to the guys who want to transform America into some European socialist state,” Hagedorn said in his closing pitch to voters.

Voters narrowly elected Hagedorn.

Fair or not, this is a big red flag for Sanders in similar districts. Voters favored over-the-top jingoistic nationalism over a bona fide combat veteran. They rejected a free-market capitalist who offered incremental improvements to health-care coverage because he was merely labeled a socialist.

Regardless of the merits, how will those same voters react when the attack ads come for Sanders, a self-avowed socialist who is on video praising Cuba’s revolution and the youth programs of the Soviet Union? And how will the well-educated staff at the Mayo Clinic — those who, based on demographics, should be easy converts for the Democratic candidate — respond to a candidate who promises to upend the health-care system completely?

Former secretary of state Hillary Clinton narrowly won Minnesota, by just 1.5 percentage points, in 2016. The state is likely to stay in the Democrats’ column in 2020, too. But if Trump runs up the score in the 1st Congressional District, the race will instantly become competitive. And if Minnesota turns red (for the first time since 1972), Trump’s path to the White House gets a lot clearer.

Plus, if Democrats want to retain the House, it would help to win districts such as Minnesota’s 1st. Feehan is gearing up for a rematch with Hagedorn this November. Having Sanders on top of the ticket would likely hurt his chances.

The 2016 election taught us humility. Perhaps Sanders could win Minnesota — and the 1st Congressional District — in a landslide. Nobody really knows. But there are serious warning signs for Sanders in Midwestern swing districts. Democrats would be foolish to ignore them.

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